Process for the production of dyed crimped yarns

ABSTRACT

THE INVENTION RELATES TO A TEXTURING PROCESS FOR THE PRODUCTION OF DYED, CRIMPED YARNS FROM ENDLESS FILAMENTS BY THE FALSE-TWIST METHOD. THE ENDLESS FILAMENTS CONSIST OF SYNTHETIC POLYMERS, SUCH AS HIGH-MOLECULAR WEIGHT LINEAR POLYAMIDES OR HIGH-MOLECULAR WEIGHT LINEAR POLYESTERS. THE PROCESS IS CARRIED OUT BY MAKING UP THE ENDLESS SYNTHETIC FILAMENTS ISSUSING FROM A SPINNING STATION BY KNITTING INTO A TUBULAR STRUCTURE, BEING DYED IN THAT FORM, THE FILAMENTS THEN BEING STRETCHED AND FALSE-TWIST-CRIMPED. THE KNITTING MACHINE REQUIRED TO PRODUCE THE TUBE IS ARRANGED IMMEDIATELY BENEATH THE SPINNING STATION. THE FALSETWISTING IS EFFECTED AT TEMPERATURES OF ABOVE 100*C.

United States "1111? US. Cl. 57-157 TS 3 Claims ABSTRACT OF THEDISCILUSURE The invention relates to a texturing process for theproduction of dyed, crimp yarns from endless filaments by thefalse-twist method. The endless filaments consist of synthetic polymers,such as high-molecular weight linear polyamides or high-molecular weightlinear polyesters. The process is carried out by making up the endlesssynthetic filaments issuing from a spinning station by knitting into atubular structure, being dyed in that form, the filaments then beingstretched and false-twist-crimped. The knitting machine required toproduce the tube is arranged immediately beneath the spinning station.The falsetwisting is effected at temperatures of above 100 C.

This invention relates to a process for the production of dyed crimpyarns from fully synthetic endless filaments, in which the filaments aredyed after spinning from the duct and are then further processed intocrimp yarn.

When texturing is carried out by the false-twist process, there are atpresent two alternative methods for producing coloured crimp filaments.The completed crimp yarn is dyed either after texturing in strand formor making up in soft cross-wound bobbins (muff), or before texturing oncross-wound bobbins. Polyamide and polyester fibres are usually dyedafter texturing since, with these materials, dyeing before texturingresults in a poor yarn yield because the crystallinity of the materialis increased under the eflect of the heat-treatment during dyeing andthe filament is fully shrunk. By contrast, polyacrylonitrile yarns aredyed before texturing.

The present practice of dyeing polyamide and polyester yarns after theyhave been textured involves a number of operations. Highly elastic crimpyarns intended for highly elastic articles are dyed in skein form sothat the elasticity is not affected by dyeing, whilst crimp yarnsintended for medium-stretch articles are dyed in the soft cylindricalmake-up, in which case the reduction in the elasticity of the yarnaccompanying dyeing is of advantage to application in this field.Hitherto, moderately elastic crimp yarns, produced on false-twistmachines, have only been satisfactorily dyed in special made-up formsbecause dyeing in the soft make-up readily produces differences inVolume between the inner and outer layers of the bobbin.

The operations involved in the roduction of crimped and dyed highlyelastic polyamide and polyester yarns for use in highly elastic articlesare as follows:

(1) Spinning on to cylindrical cross-wound bobbins,

(2) Stretching on cops or cylindrical cross-wound bobbins,

(3) Texturing a highly elastic crimp yarn on cylindrical cross-woundbobbins,

(4) Twisting together yarns with an S- and Z-crimp tendency,

(5) Preparing the skein (max. skein weights approx.

(6) Steaming,

(7) Multiple yam dyeing,

3,6l MM Patented Uct. TE, 1971 (8) Winding, (9) Making up into cones.

Twisting before the skein is made up is absolutely essential because itis extremely difficult to finish yarn that has been dyed in single yarnform (monofilaments) in the skein inasmuch as the material becomestangled and gives rise to difficulties in take-off.

Moderately elastic crimp yarns are used in the manufacture of outerclothing. With such materials, the following operations are involved:

(1) Spinning on to cylindrical cross-wound bobbins,

(2) Stretching 0n cops or cylindrical cross-wound bobbins,

(3) Texturing a highly elastic crimp yarn made up in a soft cylindricalform (max. bobbin weights approx. 600 g.),

(4) Steaming,

(5) Single yarn (monofilaments) dyeing accompanied by a reduction inelasticity,

(6) Off-wind with rollers.

(1) Spinning,

(2) Stretching,

(3) Texturing,

(4) Preparing a special dye package,

(5) Steaming,

(6) Single yarn dyeing (max. bobbin weights approximately 800 g.),

(7) Winding or in the case of plied yarn processing,

twisting and making up.

In this instance, also, finishing the special dye packages in the caseof single yarn dyeing involves numerous yarn brea'kages and hencedifficulties. Accordingly, it is also standard practice with plied yarnprocessing, to carry out the twisting operation before the special dyepackage is prepared and to dye the plied yarn in twisted form.

In none of the processes described above is it possible to process dyedand undyed yarns in admixture with one another because, on completion ofdyeing, the material is fully shrunk, whilst the undyed material shows aresidual shrinkage of from 4 to 6%, depending on the conditions underwhich it has been prepared.

When dyeing is carried out before texturing, a practice confined solelyto polyacrylonitrile filaments, the following operations are currentlyinvolved:

(1) Spinning on to cylindrical cross-wound bobbins,

(2) Stretching,

(3) Fully shrinking the material,

(4) Winding to form dye packages (maximum package weights approximately1 kg),

(5) Single yarn dyeing,

(6) Texturing on cylindrical cross-wound bobbins and, with plied yarnprocessing, twisting and making up.

In this instance, too, dyed and undyed material can only be processed incombination with one another if the undyed material has also been fullyshrunk before texturing.

A process for the production of dyed crimp yarns by the false-twistmethod has now been found in which hitherto-essential operations can beeliminated, providing the endless filaments issuing from the extrusionspinnerette are made up into a knitted tubular structure, are dyed inthis tubular form, and are then stretched and false-twistcrimped in asingle operation. Dyed and undyed material can also be processed inadmixture with one another, be cause the residual shrinkage aftertexturing is the same in both yarns. For this purpose, the spun materialis made up and dyed in tubular form. This spun material can be stretchedand crimped in a single operation on the false twist texturing machine.The knitting machine required to produce the tube is arrangedimmediately beneath the spinning duct. Deformation of the loopsaccompanying preparation of the tubular structure is eliminated by thestretching operation. Dyeing can be carried out in known manner bothwith the package system and also with the creel system. This process issuitable for polyamide, polyester and polyacrylonitrile filaments.False-twisting is effected at temperatures of above 100 C.

The following examples show that this novel process affords considerableadvantages. By reducing, the number of operations involved and also byvirtue of the fact that mixed-yarn processing is possible, considerableeconomy can be achieved especially when the stretch-crimping principleis adopted.

EXAMPLE 1 A 140-denier with 18 filaments polyamide crimp yarn ofmoderate elasticity is required for use in knitting to produce a knittedarticle (Wevenit). It is spun with a spinning denier of 427 denier anddirectly made up into a tubular structure on a l-gg knitting machine.This tubu lar structure is dyed by the creel method and stretched on atexturing machine with 2 texturing zones in a stretching ratio of 13.2at 1800 r.p.m./160 C. and false-twistcrimped at 150 C. with an overfeedof 4% at 2000' t./m.

EXAMPLE 2 A moderately elastic 90* denier 4-plied crimp yarn ofpolyamide-6 is required for use in the cotton sector. It is spun with adenier of 315 denier and directly made up into a tubular structure on aknitting machine. After dyeing in the tubular structure, the yarn isstretched on a texturing machine with 2 texturing zones in a ratio of113.12 at 1600 revolutions/150 C. and then false-twist crimped at 160 C.and 3000 t./m. with an overfeed of 9%. This material is twisted andconed in 4-plied form.

4 EXAMPLE 3 A 90 denier polyamide crimp yarn is required for use in theproduction of highly elastic sock yarns. It is spun with a denier of 315denier and directly made up into tubular form. This material is dyed intubular structure. After stretching in a ratio of 1:3.5 on a standarddrawing machine, the yarn is false-twisted at 3000 t./m. at 180 C. undera 6 overfeed on a standard false-twist machine.

EXAMPLE 4 A 240 denier polyacrylonitrile crimp yarn is required for theproduction of outer clothing. It is used in a spinning denier of 860'denier. This material is made up into a tubular structure on a 10-ggknitting machine and then dyed. After dyeing, the tubular structure isfed directly to a false-twist texturing machine incorporating astretching frame, stretched in a stretching ratio of 1:5.5 at 160 C. andthen false-twisted at 1560 t./m. at 170 C. with a 3% overfeed.

What we claim is:

1. A process for the production of dyed crimp yarns from fully syntheticendless filaments by the false-twist method, which comprises extrudingendless filaments from an extrusion spinnerette, knitting the same intoa tubular structure, dyeing the filaments in said tubular structure andthen stretching and false-twist crimping said filaments.

2. The process as claimed in claim 1, wherein a knitting machine isarranged immediately beneath the extrusion spinnerete.

3. The process of claim 1 wherein the stretching and false-twistcrimping are carried out in a single operation.

References Cited UNITED STATES PATENTS JOHN PETRAKES, Primary ExaminerU.S. Cl. X.R.

